abstract: Water quality is a severe problem throughout the world. Much available water is contaminated by pathogenic microbes. This project reviews the traditional process of solar water disinfection in bottles (SODIS), discusses experiments conducted with SODIS bottles modified to thermally enhance the process, analyzes experimental data for modified SODIS containers, and suggests ways that by which the traditional process can be improved. Traditional SODIS is currently used in many rural parts of developing countries to disinfect water. The process uses ultraviolet rays and thermal effects to inactivate microorganisms that tend to cause diarrheal disease. If a sufficiently high temperature is attained to reach a synergistic UV-thermal effect range, the process of SODIS is about three times faster. However, many factors can inhibit attainment of sufficient heating of water in SODIS bottles in practice. By modifying the bottles to enhance effectiveness of sunlight in increasing the temperature of the water, SODIS can be more effective. In this research, a series of experiments were conducted over a period of four months and15 days at Arizona State University Polytechnic campus in Mesa, Arizona, U.S.A. Four different types of inexpensive materials (black paint, white paint, foam insulation, and aluminized mylar) were used individually or in combination in seven different modified configurations to assess the potential of the modifications to increase the temperatures of water inside 2-liter PET bottles. Experiments were run in triplicate. Temperatures inside the bottles, along with yard temperature, were recorded over time. Graphs were plotted for each set of experiments. The results of these experiment show that several types of modifications increased water temperature during exposure to sunlight. Water in bottles with black paint and foam insulation on the back side attained the highest temperatures, approximately 8-10 degrees Celsius above temperatures attained in plain bottles. The results of these experiments show how several inexpensive, easily obtained materials can significantly enhance the SODIS process. / Dissertation/Thesis / M.S. Applied Mathematics 2011

Made available in DSpace on 2014-06-11T19:29:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-18Bitstream added on 2014-06-13T19:17:32Z : No. of bitstreams: 1 pereira_rp_me_arafo.pdf: 718418 bytes, checksum: e3bb9ad8e88ee0f369f92dd6e3ca7045 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Vários protocolos de desinfecção podem ser usados para romper a cadeia de infecção cruzada entre o consultório odontológico e o laboratório de prótese. A inclusão de agentes antimicrobianos à composição do gesso ou a manipulação do gesso com soluções desinfetantes podem ser usados com esta finalidade. O propósito deste estudo foi avaliar a atividade antimicrobiana de dois agentes desinfetantes (digluconato de clorexidina 2% e cloridrato de clorexidina 98%) incorporados ao gesso IV (FujiRock - GC Europe, Leuven, Bélgica) durante sua manipulação. No teste microbiológico de difusão em Agar foram uti l izados os seguintes microorganismos: Escherichia coli, Staphylococcus aureus, Bacilus subtilis e Candida albicans. Amostras com 5 mm de diâmetro e 3 mm de espessura foram separadas em quatro grupos: 1) gesso manipulado com água destilada esterilizada (controle positivo); 2) discos de papel embebidos com solução de digluconato de clorexidina 2% (controle negativo); 3) gesso manipulado com solução de digluconato de clorexidina 2%; 4) gesso com a incorporação de cloridrato de clorexidina 98% em pó, na proporção de 1% da massa do gesso, e manipulado com água destilada esterilizada. Após 1 hora e 24 horas do vazamento do gesso, as amostras foram posicionadas em placas de Petri com meios de cul tura específicos inoculados com as suspensões microbianas. A atividade antimicrobiana dos desinfetantes foi avaliada pelo diâmetro médio dos halos de inibição do crescimento microbiano. Os valores foram analisados pela ANOVA Aninhada (p<0,05) e teste de Tukey para comparações específicas. Os resultados encontrados demonstraram que os agentes desinfetantes analisados apresentaram atividade antimicrobiana quando misturados ao gesso, com exceção para Candida albicans, na qual não houve efeito da solução de clorexidina nos dois períodos de análise... / Many protocols for disinfection procedures can be used to break the chain of cross-contamination between dental office and dental laboratory. The inclusion of antimicrobial agent to the composition of gypsum or the manipulat ion of gypsum with disinfectant substances can be used to that aim. The purpose of this study was to evaluate the antimicrobial activity of two disinfectant agents (2% chlorhexidine digluconate and 98% chlorhexidine hydrochloride) incorporated into type IV dental stone (FujiRock - GC Europe, Leuven, Belgium) at the time of mixing. The microbiological test used was the Agar diffusion test to the following microorganisms: Escherichia coli, Staphylococcus aureus, Bacilus subtilis and Candida albicans. Samples of 5 mm in diameter and 3 mm in length were separated in four groups: 1) dental stone mixed wi th steri le distilled water (positive control); 2) paper disk soaked wi th solution of 2% chlorhexidine digluconate (negative control); 3) dental stone mixed with solution of 2% chlorhexidine digluconate; 4) dental stone wi th incorporation of chlorhexidine hydrochloride 98% powder, in proportion of 1% of the dental stone mass, and mixed with sterile distilled water. The samples were placed, 1 hour and 24 hours after pouring of dental stone, in Petri plates with specific cul ture medium wich were inoculated with the microbial suspensions. The antimicrobial activity of disinfectant was evaluated by the average diameter of microbial growth inhibi tion zones. The data were analyzed with a Nested ANOVA (p<0,05) and Tukey test for specific comparisons. The disinfectant agents analyzed demonstrated antimicrobial effect against microorganisms used in this study, in exception to Candida albicans, against wich there was not effect from chlorhexidine digluconate at two periods of analysis. Significant difference between disinfectantes were found to all microrganisms... (Complete abstract click electronic access below)

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15346号 / 工博第3225号 / 新制||工||1485(附属図書館) / 27824 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 伊藤 禎彦, 教授 津野 洋, 教授 田中 宏明 / 学位規則第4条第1項該当

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Richard D. Oberst / Viruses differ in their susceptibility and resistance to disinfectants and their ability to be inactivated based predominantly on structural and size differences. The virucidal methodology followed in this study was consistent with the U.S. Environmental Protection Agency guidelines for such efficacy testing. Various disinfectant chemistries were effective in rapid and complete inactivation of bovine coronavirus (BCV) including 25, 50, and 100% DF-200d, 10% bleach, 1% Virkon® S, and 70% ethanol following 10 min treatments. Efficacy was slightly reduced in the presence of organic challenge material (feces, soil). Treatment with 100% DF-200d or 10% bleach resulted in the degradation of BCV RNA. Treatment with 50 or 100% DF-200d, 10% bleach, or 1% Virkon® S resulted in the degradation of BCV proteins as detected by western blot analysis. Various disinfectants were effective in the complete inactivation of both mammalian and avian influenza test strains and included DF-200d, 10% bleach, 1% Virkon® S, and 70% ethanol following 10 min exposure but was reduced in the presence of organic challenge. Treatment with DF-200d or 10% bleach resulted in significant degradation of influenza RNA. Effective treatments against foot-and-mouth disease virus (FMDV) and bovine enterovirus-2 (BEV-2) included 10% bleach, 4% sodium carbonate, 2% sodium hydroxide, and Sandia DF-200. Treatment with 5% acetic acid was effective against FMDV, but not BEV-2. Treatment with 70% ethanol was not effective for inactivating FMDV or BEV. Additionally, 10 min treatment with 10% bleach, 2% sodium hydroxide, and Sandia DF-200 degraded FMDV and BEV-2 RNA. FMDV inoculated surfaces were exposed to 5% acetic acid, 10% bleach, 70% ethanol, 4% sodium carbonate, 2% sodium hydroxide, Sandia DF-200, 0.4% Oxy-Sept® 333, or 1% Virkon® S. All treatments except 70% ethanol were effective following 10 and 20 min contact on rubber and stainless steel. No treatments were shown to be effective for concrete, due to a low recovery of virus from this surface. Additionally, 10 and 20 min treatments with 10% bleach, 2% sodium hydroxide, and Sandia DF-200 degraded FMDV RNA on the surfaces evaluated.

Magister Scientiae (Medical Bioscience) - MSc(MBS) / The aim of this study was to evaluate the effectiveness of water treatment processes of two drinking water plants to remove immunotoxins and steroid hormones. Raw and treated drinking water was screened for effects on inflammatory activity using the biomarker IL-6, humoral immunity using the biomarker IL-10 and cell mediated immunity using the biomarker FN-γ. In vitro human whole blood culture assays were used in order to elucidate potential immunotoxicity. / South Africa

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With the increasing interest in the indoor air environment over the last 30 years has come the need for control devices that can improve the quality of air that people breath. To answer this need, many devices have been developed and are currently in use. This thesis utilizes Ultra-violet light to eradicate the bacteria. A portable unit was constructed that contains the light bulb and fan. Two different trials were conducted: Controlled Laboratory trials and Fish Culture Room Trials. The Controlled Laboratory Experiments were conducted in order to test the effect that the Ultra-violet unit had on known cultures of bacteria while the Fish Culture Room Trials were conducted to test the chambers affect on a real indoor situation. The Ultra-violet unit was effective in eradicating the known cultures that were tested, and was less effective in the real indoor setting. As the density of bacteria increased, the effectiveness of the chamber increased, for the real indoor setting. The contact time of the chamber could be adjusted to improve effectiveness. More testing is necessary to fully evaluate the potential of a portable Ultra-violet disinfection chamber. / Master of Science

Nitrification is a significant concern for drinking water systems employing chloramines for secondary disinfection. Utilities have implemented a range of disinfection strategies that have varying levels of effectiveness in the prevention and control of nitrification events, including optimizing the chlorine-to-ammonia ratio, maintaining chloramine residual throughout the distribution system, controlling pH, and temporal switching to free chlorination. Annual or semi-annual application of free chlorination is practiced by 23% of chloraminating systems on a temporary basis as a preventative measure, even though it has the undesirable consequences of temporarily increasing disinfection byproducts, facilitating coliform detachment, and altering water taste and odor. Although temporal free chlorination and other nitrification control methods have been widely studied in the field and in pilot-scale systems, very little is known about the stress responses of nitrifying bacteria to different disinfection strategies and the role physiological state plays in the resistance to disinfection. It is well known that many commonly studied bacteria, such as Escherichia coli, are able to better resist disinfection by free chlorine and chloramines under nutrient limitation through regulation of stress response genes that encode for DNA protection and enzymes that mediate reactive oxygen species. We compared the genomes of E. coli and the ammonia-oxidizing bacterium Nitrosomonas europaea, and found that many of the known stress response mechanisms and genes present in E. coli are absent in N. europaea or not controlled by the same mechanisms specific to bacterial growth state. These genetic differences present a general susceptibility of N. europaea to disinfection by chlorine compounds. Using an experimental approach, we tested the hypothesis that N. europaea does not develop increased resistance to free chlorine and monochloramine during starvation to the same degree as E. coli. In addition, N. europaea cells were challenged with sequential treatments of monochloramine and hypochlorous acid to mimic the disinfectant switch employed by drinking water utilities. Indicators of activity (specific nitrite generation rate) and viability (LIVE/DEAD® BacLight© membrane-integrity based assay) were measured to determine short-term effectiveness of disinfection and recovery of cells over a twelve day monitoring period. The results of disinfectant challenge experiments reinforce the hypothesis, indicating that the response of N. europaea to either disinfectant does not significantly change during the transition from exponential phase to stationary phase. Exponentially growing N. europaea cells showed greater susceptibility to hypochlorous acid and monochloramine than stationary phase E. coli cells, but had increased resistance compared with exponential phase E. coli cells. Following incubation with monochloramine, N. europaea showed increased sensitivity to subsequent treatment with hypochlorous acid. Complete loss of ammonia-oxidation activity was observed in cells immediately following treatment with hypochlorous acid, monochloramine, or a combination of both disinfectants. Replenishing ammonia and nutrients did not invoke recovery of cells, as detected in activity measurements during the twelve day monitoring period. The results provide evidence for the effectiveness of both free chlorine and chloramines in the inhibition of growth and ammonia-oxidation activity in N. europaea. Furthermore, comparison of viability and activity measurements suggest that the membrane integrity-based stain does not serve as a good indicator of activity. These insights into the responses of pure culture nitrifying bacteria to free chlorine and monochloramine could prove useful in designing disinfection strategies effective in the control of nitrification. / Master of Science

The results from this study show how different precursors affect halonitromethane (HNM) formation as well as how different free chlorine doses can affect HNM speciation. This study shows that the low pressure ultraviolet (LPUV) and free chlorine concurrent exposure can enhance HNM formation. In addition, most previous studies in the literature showed trichloronitromethane (TCNM) forming in greater quantities followed by monochloronitromethane (MCNM) and dichloronitromethane (DCNM). However, the results of this study show that, in deionized (DI) water matrices, MCNM forms in greater quantities at chlorine to nitrogen (Cl:N) ratios less than 3, while TCNM forms in greater quantities at Cl:N ratios greater than 3. Even so, the increase in TCNM formation did not increase linearly as the Cl:N ratio increased; there was a decreased rate of return when Cl:N ratios were greater than 3. The type of nitrogenous precursors can affect the amount of HNMs formed, with glycine forming a higher amount of total HNMs compared to methylamine (MA) and dimethylamine (DMA). The source of water can also affect which HNM species is formed in greater concentrations. The limited number of real water samples showed that the river waters have higher than normal total organic carbon (TOC) and dissolved organic nitrogen (DON), which are associated with greater nitrogenous precursors and higher HNM formation. Each water source can have different nitrogenous precursors; river waters may have more algal organic matter while wastewater would have higher organic matter and synthetic chemicals. In addition, source waters can have different constituents, such as varying dissolved oxygen (DO) levels and inorganic ions, which might inhibit HNM formation or affect specification.